A sensor device, in particular a pressure sensor

ABSTRACT

A pressure-sensor device ( 1 ) comprises: a pressure-sensitive component ( 5, 5   a,    6 ), having a sensor body ( 5 ) that includes an elastically deformable membrane part ( 5   a ) and at least one detection element ( 6 ) suitable for detecting a deformation of the membrane part ( 5   a ); a supporting structure ( 2, 3 ) for supporting the pressure-sensitive component ( 5, 5   a,    6 ), having a passageway ( 15 ) for a fluid of which a pressure is to be measured. The supporting structure ( 2, 3 ) comprises: a supporting body ( 2 ) with respect to which the sensor body ( 5 ) is positioned in such a way that its membrane part ( 5   a ) is exposed to the fluid exiting the passageway ( 15 ), the supporting body ( 2 ) having at least one through cavity ( 14 ), a compressible body ( 16 ), which is configured for compensating possible variations of volume of the fluid. The supporting body ( 2 ) has a first body portion ( 2   c ) comprising a transverse wall ( 22 ) of the through cavity ( 14 ), defined in which is at least one first passage ( 23   a - 23   b ) and at least one second passage ( 24 ), the at least one first passage ( 23   a - 23   b ) belonging to the passageway ( 15 ) for the fluid. The compressible body ( 16 ) is an element over-moulded with respect to the supporting body ( 2 ), that has respective opposite portions ( 20, 21 ) which extend in positions corresponding to opposite sides of the transverse wall ( 22 ), and which are connected to one another via at least one intermediate portion ( 16   a ) of the compressible body ( 16 ) that that extends through the at least one second passage ( 24 ). The first body portion ( 2   c ) is shaped to define at least one step or one projection or one relief ( 25; 28 ) which determines at least one of: a cross-sectional narrowing of the at least one second passage ( 24 ), configured to define a corresponding cross-sectional reduction of the at least one intermediate portion ( 16   a ) of the compressible body ( 16 ), and a development of the at least one intermediate portion ( 16   a ) of the compressible body ( 16 ) which is generally tortuous or comprises a number of stretches substantially angled to each other.

FIELD OF THE INVENTION

The present invention relates to pressure-sensor devices and has beendeveloped with particular reference to sensor devices that comprise apressure-sensitive element having an elastically deformable membrane,associated to which is an element for detecting deformation of themembrane.

PRIOR ART

A sensor device having the characteristics referred to in the preambleof claim 1 is known from WO2008/078184 A2 filed in the name of thepresent Applicant.

The above document describes a pressure-sensor device, the sensitivecomponent of which has a sensor body with a blind cavity, the bottom ofwhich is formed by a membrane part. The membrane part is elasticallydeformable and associated thereto is a detection element, such as abridge of resistive or piezoresistive elements. The device has a casingmade of a number of parts, amongst which a supporting body for thesensor body. The supporting body is axially traversed by a cavity, theinlet end of which is in a position corresponding to a hydraulicattachment portion of the casing, the outlet end of the through cavityfacing, instead, the cavity of the sensor body, i.e., of its membranepart.

In certain applications, devices of the type referred to above operatein conditions of very low temperature, and it may occasionally occurthat the fluid the pressure of which is to be detected freezes, thusincreasing in volume. Given that the membrane part of the sensor body isusually relatively thin and delicate, it is important to adopt solutionsthat may prevent its failure and/or damage to the correspondingdetection element following upon increase in volume of the fluid due tofreezing. The aforesaid prior document consequently proposes associationto the supporting body of one or more compressible compensation bodies,i.e., elements suitable for compensating possible increases in volume ofthe fluid following upon freezing thereof.

The solution known from WO2008/078184 A2 envisages the use of “external”compensation elements, i.e., ones mounted on the outside of thesupporting body, substantially at the cavity of the sensor body, i.e.,in the proximity of its membrane part, or else “internal” compensationelements, i.e., ones directly inserted in the through cavity of thesupporting body, at a certain distance from the membrane of the sensorbody, where the aforesaid compensation elements each have a throughaxial duct, which provides a respective part of the passageway for thefluid undergoing detection.

The aforesaid document also suggests the possibility of forming aninternal compensation element and an external compensation element in asingle compressible body. This single compressible body is, by itsnature, compliant (yielding), and this enables mounting thereof on thesupporting body, with a corresponding part inside its through cavity andanother part on the outside of this cavity, so as to project into thecavity of the sensor body. According to possible variant embodimentsdescribed in WO2008/078184 A2, the aforesaid single body may also beconfigured as part overmoulded on the supporting body of the device. Inthese known solutions, the through cavity of the supporting body has anintermediate transverse wall defining a narrowing or restriction of thecavity itself, necessary for guaranteeing anchorage of the aforesaidsingle body.

In the devices produced according to WO2008/078184 A2, in which aninternal compensation element and an external compensation element areformed in a single body, the pressurized fluid at inlet to the deviceexerts a direct thrust at the lower end and/or on some walls of theinternal compensation element. Given that the compressible body is madeof a relatively yielding material—such as a silicone—these axial and/orradial thrusts of the fluid may determine over time a displacement of atleast part of the yielding material towards the sensitive element, i.e.,a sort of extrusion of at least part of the compressible body that formsthe two compensation elements. For instance, the present Applicant hasfound that, in particular conditions—such as high pressures of the fluidin the system to which the sensor is connected (e.g., in the case of thephenomenon known as “water hammer”) that may occasionally occur—thethrust of the fluid at high pressure may exceed the limit of compressionof the compressible element, the internal structure of which may becompacted to the point where it is displaced at least in part as aresult of the thrust of the fluid, in turn transferring the thrust ontoother internal areas of the structure of the sensor.

The above displacement or extrusion of at least a part of theinternal-compensation body gives rise to a deformation of the yieldingmaterial in regions close to the sensitive element, thereby causing athrust of the material itself directly on the membrane part, withconsequent alterations of the reliability of measurement of the deviceor failure of the membrane part itself. The problem is exacerbated inthe case where the operating temperatures, i.e., the ambient temperatureand/or the temperature of the fluid, are relatively high, given that inthese conditions the material of the compensation element tends initself to increase in volume and/or increase its yielding.

In various embodiments described in the aforesaid prior document, thedevice is moreover built so as to define, along the passageway of thefluid the pressure of which is to be detected, one or more capillarypassages, or in any case passages having a reduced section. Provision ofthese passages is aimed at imposing beforehand, with relative precision,one or more regions in which the fluid will start to freeze, with thepossibility then of causing freezing in the areas of the passageway forthe fluid having a wider section, i.e., in a direction opposite to themembrane portion of the sensitive component. Provision of thesecapillary passages complicates production of the device, for example onaccount of the fact that to its supporting body there must be associatedadditional purposely shaped inserts. Notwithstanding the presence ofthese passages with reduced section, the pressurized fluid in any caseexerts a direct thrust on the membrane of the sensitive element. Forthis reason, in the case of freezing of the fluid within thecorresponding passageway, the increase in volume of the fluid followingupon freezing thereof determines a significant thrust in an axialdirection towards the membrane, with consequent risks of damage.

Aim and Summary of the Invention

In view of the foregoing, the present invention is aimed at providing apressure-sensor device of the type referred to above, in which the risksof alteration of the measurement and/or of damage to the sensingmembrane are eliminated, or at least reduced further.

In the above context, a main aim of the present invention is to providea pressure-sensor device of the type referred to above, where the thrustexerted by the pressurized fluid on a compressible body that isovermoulded or co-moulded and/or defines two compensation elements doesnot cause any deformation and/or extrusion of the yielding material thatforms the aforesaid compressible body, such as to adversely affect thereliability of detection of the device.

An auxiliary aim of the present invention is to provide apressure-sensor device of the type referred to above, where the thrustexerted by the icy fluid does not cause deformations or damage such asto adversely affect the reliability of detection of the device and/ordoes not cause failure of its membrane.

Another auxiliary aim of the present invention is to provide apressure-sensor device of the type referred to above that can beproduced in a simple, fast, and economically advantageous way.

One or more of the aforesaid aims is achieved, according to the presentinvention, by a pressure-sensor device having the characteristicsspecified in the annexed claims. The claims form an integral part of thetechnical teaching provided herein in relation to the invention.

A pressure-sensor device according to the invention has a body thathouses or supports a pressure-sensitive element, associated to which isat least one compressible body designed to compensate any possibleincrease in volume of the fluid undergoing detection.

The aforesaid body, defined hereinafter for simplicity also as“supporting body”, has a through cavity and at least a first bodyportion thereof is provided with detent means, in particular at a walltransverse with respect to the through cavity. The aforesaid bodyportion, or the transverse wall, is traversed by at least one firstpassage that, together with a duct defined at least in part by the atleast one compressible body, belongs to the passageway for the fluid thepressure of which is to be detected. The compressible body is an elementovermoulded or co-moulded with respect to the supporting body andpreferably has respective opposite portions which extend at oppositesides of the transverse wall, wherein said opposite portions areconnected to each other by means of at least one restricted portion ofthe compressible body that extends through at least one second passagedefined in the transverse wall. The at least one restricted portion ispreferably in an intermediate position with respect to compensationelements having greater sizes, formed by a single compressible body.

The aforesaid portion of the supporting body is preferably shaped so asto define at least a step, or a projection, or relief, which determinesat least one of:

a narrowing of section of the at least one second passage, configuredfor defining a corresponding reduction of section of the at least oneintermediate portion of the compressible body, and

a generally tortuous development of the at least one intermediateportion of the compressible element, in particular comprising a numberof stretches substantially angled with respect to one another.

These characteristics, i.e., the definition of suitable means for arrestand/or retention of the position of the compressible body, enable toavoid the risks tied to possible extrusion or displacement of theovermoulded or co-moulded compressible body. The cited narrowingdetermines a corresponding restriction of the thickness of theconnection portion that joins the two opposite portions of thecompressible body, limiting thereby the effects of a possible extrusionor displacement of the material. The same applies to the case of asecond passage that is as a whole tortuous or has stretches angled withrespect to one another. The aforesaid step (or projection or radial ortransverse relief) likewise determines the presence of at least onesurface upon which the corresponding intermediate portion of thecompressible body partially comes to bear, thereby further counteringpossible extrusion of the material that constitutes it.

Additionally, in this way, the compressible body may conveniently beovermoulded on or co-moulded with the supporting body and withheld inposition. For this purpose, in advantageous embodiments such as the onesreferred to in claim 12, the transverse wall may define a plurality ofsecond passages, through which there extend respective intermediateportions of the compressible body, to the advantage of the mouldingoperations (the flow of the material is more convenient), of the qualityof connection between the two portions of the compressible element whichare in opposite positions with respect to the transverse wall, and offixing in position with respect to the supporting body.

At least one second passage for the material that provides acorresponding intermediate portion of the single compressible body ispreferably defined in a peripheral position with respect to a firstpassage of the transverse wall, designed, instead, for the fluid thepressure of which is to be detected; the at least one second passagecould, however, be defined in some other position, for example a centralposition with respect to the at least one passage for the fluidundergoing detection.

As indicated in claim 2, the compressible body may be overmoulded suchas to define at least one of a first compensation element, set at leastpartially within the through cavity of the supporting body upstream ofthe transverse wall, and a second compensation element, set downstreamof the transverse wall, in a position close to the membrane of thesensitive element, wherein the first and/or the second compensationelement each define at least one duct for the fluid, or else delimits atleast one duct for the fluid together with a corresponding part of thesupporting body. In the case of freezing of the fluid, the firstcompensation element enables compensation of the increase in volume ofthe fluid in the preponderant part of the passageway, whereas the secondcompensation element makes a compensation in the most critical point,i.e., in the proximity of the membrane. The protection is maximum in thecase of coexistence of both of the compensation elements, as inembodiments of the type referred to in claim 3, wherein the two oppositeportions of the compressible element provides the aforesaid first andsecond compressible elements, overmoulded as a single compressible body.

In various embodiments, such as those referred to in claim 4, the firstbody portion of the supporting body comprises at least one projecting orcantilever wall of the through cavity, set downstream of the transversewall, which extends towards the inside of the through cavity itself soas to define at least in part the aforesaid step (or projection orrelief). This characteristic simplifies definition of the above step,preventing the presence of undercuts or recesses and thereby simplifyingproduction of the supporting body, in particular when this is a mouldedbody of plastic material. As an alternative or in addition to theaforesaid projecting wall, the transverse wall may include a narrowingof section for the same purposes indicated above.

Preferably, as indicated in claim 5, the first body portion of thesupporting body is shaped so as to define the at least one step orprojection or relief in a position corresponding to at least one endregion of the at least one second passage: this simplifies constructionof the passage itself, in particular when the supporting body is amoulded body. Very advantageously, the first body portion of thesupporting body may be shaped to define at least two steps (orprojections or radial or transverse reliefs) in opposite end regions ofthe second passage. In this way, possible effects of extrusion ordisplacement of the material that forms the two compensation elementsare further countered, while simplicity of construction of thesupporting body remaining the same.

The simplicity of construction of the supporting body, in particularwhen this body is obtained by moulding of plastic material, is maximumwhen each second passage is obtained through cavities which each have arespective bottom and are staggered with respect to one another butintersect, defining prevalently lateral openings, for example as in thecase of the embodiments of claim 7. An embodiment of this sort, inaddition to being simple, enables effective definition of a generallytortuous development of the at least one intermediate portion of thecompressible element, in particular comprising a number of stretchessubstantially angled with respect to each other.

In various embodiments, such as those indicated in claim 8, the at leastone first passage for the fluid has at least one respective inlet and atleast one respective outlet, which are arranged so as to define atortuous path for the fluid. The aforesaid tortuous path considerablyreduces the direct thrust of the fluid on the membrane of the sensitiveelement, in particular when the fluid is icy, and the consequent risksof the prior art deriving from possible freezing of the fluid itself. Inembodiments of this type, and as indicated in claim 9, it is preferablethat the at least one inlet of the first passage is in fluidcommunication with the outlet end of the duct of the first compensationelement and/or the at least one outlet of the first passage is in fluidcommunication with the inlet end of the duct of the second compensationelement.

The at least one inlet and the at least one outlet of the at least onefirst passage preferably extend according to respective substantiallyparallel axes. An embodiment of this sort, in addition to being simple,enables effective definition of a tortuous path for the fluid. For thisreason, advantageously, also the at least one first passage, or eachfirst passage, may be formed by at least two cavities provided withbottom, which are staggered with respect to one another and intersectlaterally.

By and large, the same advantages may be obtained also in embodiments ofthe type referred to in claim 10, i.e., where the at least one firstpassage has at least two inlets connected to one and the same outlet, orelse one inlet connected to at least two outlets. For such cases, afirst compensation element upstream of the transverse wall of thethrough cavity and/or a second compensation element downstream of theaforesaid wall may be provided with one or two respective cavities, asindicated in claim 11.

In preferential embodiments, such as those referred to in claim 13, thethrough cavity of the supporting body is shaped so as to define,downstream of the transverse wall, a housing portion, partially housedwithin which is a compensation element close to the sensitive component.In this way, the quality of positioning of the aforesaid compensationelement is increased and any lateral expansion thereof following uponfreezing and dilation of the fluid are limited. Preferably, a wall thatperipherally delimits the aforesaid housing has one or more reliefs thatperform the function of retention of the compensation element.

In various embodiments, such as those referred to in claim 14, theperipheral surface of the through cavity of the supporting body isshaped so as to define one or more reliefs, which advantageously performa function of retention of the first compressible element and/or secondcompressible, further countering possible extrusion phenomena. Theaforesaid reliefs, which themselves provide detent means for acompressible body, may be used to advantage also in the absence of awall transverse to the through cavity of the supporting body.

In various embodiments, such as those referred to in claim 15, thepressure-sensor device comprises means for causing adhesion or bondingbetween at least one surface part of the supporting body and at leastone corresponding surface part of a compressible body. These means,which themselves perform a function of detent or retention for acompressible body, may be advantageously used also in the absencereliefs and/or of a wall transverse to the through cavity of thesupporting body.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aims, characteristics, and advantages of the invention willemerge clearly from the ensuing detailed description, which is providedwith reference to the annexed drawings and in which:

FIG. 1 is a schematic perspective view of a pressure-sensor deviceaccording to one embodiment of the invention;

FIG. 2 is a schematic longitudinal sectional view of the device of FIG.1;

FIG. 3 is a schematic longitudinal sectional view of a part of the bodyof the device of FIG. 1;

FIGS. 4-6 are perspective views from different angles of a part of thebody of the device of FIG. 1, FIG. 6 being partially sectioned;

FIG. 7 is a partial and schematic cross-sectional view of a portion ofthe device of FIG. 1;

FIGS. 8 and 9 are partial and schematic perspective views of adeformable body of a device according to possible embodiments of theinvention;

FIG. 10 is a cross section of a part of a body of a device according tothe invention, with associated a deformable body of the type illustratedin FIGS. 8-9;

FIGS. 11, 12, and 13 are cross-sectional views according to the linesD-D, C-C, and B-B of FIG. 10, respectively;

FIGS. 14-16 are exploded schematic perspective views of mouldingequipment that can be used in a process for the production of a deviceaccording to the invention, in various operating steps;

FIG. 17 is a partial and schematic sectioned view of the mouldingequipment of FIGS. 14-16, with, inside it, a part of a body of a deviceaccording to the invention;

FIG. 18 is a view similar to that of FIG. 2, regarding a furtherembodiment of the invention;

FIGS. 19-28 are views similar to those of FIGS. 2, 3, 6, 4, 5, 8, 10,11-13, respectively, regarding a further embodiment of the invention;

FIGS. 29-35 are views similar to those of FIGS. 1-6, regarding a furtherembodiment of the invention;

FIG. 36 is a view similar to that of FIG. 30, regarding a furtherembodiment of the invention;

FIGS. 37-41 are views similar to those of FIGS. 2, 3, 6, 4, and 5,respectively, regarding a further embodiment of the invention;

FIG. 42 is a view similar to that of FIG. 37, regarding a furtherembodiment of the invention;

FIGS. 43-50 are views similar to those of FIGS. 2, 3, 6, 4, 5, 8, 9, and10, respectively, regarding a further embodiment of the invention;

FIGS. 51-54 are cross-sectional views according to the lines E-E, D-D,C-C, and B-B of FIG. 50, respectively;

FIGS. 55-58 are views similar to those of FIG. 2, regarding as manyfurther possible embodiments of the invention;

FIGS. 59 and 60 are schematic longitudinal sections of devices accordingto further possible embodiments of the invention;

FIG. 61 is a partial and schematic cross-sectional view of a deviceaccording to possible further embodiments of the invention;

FIG. 62 is a detail at an enlarged scale of FIG. 61; and

FIG. 63 is a view similar to that of FIG. 62, but regarding furtherpossible embodiments of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Reference to “an embodiment” or “one embodiment” in the framework of thepresent description is intended to indicate that a particularconfiguration, structure, or characteristic described in relation to theembodiment is comprised in at least one embodiment. Hence, phrases suchas “in an embodiment”, “in one embodiment”, and the like, that may bepresent in various points of the present description, do not necessarilyrefer to one and the same embodiment, but may, instead, refer todifferent embodiments. Moreover, particular conformations, structures,or characteristics defined in the framework of the present descriptionmay be combined in any adequate way in one or more embodiments that mayeven differ from the ones represented. The reference numbers and spatialreferences (such as “upper”, “lower”, “up”, “down”, etc.) refer to theexamples appearing in the figures and are used herein merely forconvenience and hence do not limit the sphere of protection or the scopeof the embodiments.

In FIGS. 1 and 2, designated as a whole by 1 is a pressure-sensor deviceaccording to one embodiment of the invention. The device 1 has a housingor supporting structure, designed to house and/or support apressure-sensitive component. The aforesaid structure is preferablyconfigured like a casing, as in the examples illustrated, having anelectrical-connection portion and a hydraulic-connection portion.

In the case exemplified, the housing or supporting structure, alsodefined hereinafter as “casing” for simplicity, comprises two mainparts, amongst which a first body 2, defined hereinafter also as“supporting body”, preferably performing also hydraulic-connectionfunctions, and a second body 3, defined hereinafter also as “closingbody”, preferably performing housing and/or closing functions andelectrical-connection functions. In various embodiments, the parts 2 and3 contribute to defining a casing that protects the sensitive componentfrom the external environment, albeit providing at least one passagewayfor a fluid of which a pressure is to be measured, and possibly one ormore further passages towards the external environment, for example tohave available a reference pressure or to enable venting of air.

The bodies 2 and 3 are coupled together, preferably in a fluid-tightway, so as to define a space within which the pressure-sensitivecomponent is housed. As may be seen in FIG. 2, in the exampleillustrated, the sensitive component has a sensor body 5 with a membranepart 5 a, which is elastically deformable as a function the pressure ofthe fluid being measured. In what follows, for simplicity, the part 5 awill be defined also as “membrane”. The membrane 5 a may be obtainedintegrally in the sensor body 5 or else be configured as a distinct partassociated to the sensor body 5, for example via welding or gluing (forinstance, as in the case exemplified in FIG. 60).

As per the known technique, the sensitive component 5 has associated atleast one element designed to detect deformation of the membrane part 5a. The aforesaid detection element, designated by 6 only in FIG. 2, maycomprise a plurality of resistors or piezo-resistive elements, forexample in bridge configuration, preferably provided on the side of themembrane 5 a that is not exposed to the fluid the pressure of which isto be measured. In other embodiments (not represented), the detectionelement 6 may comprise electrodes and/or capacitive elements, such astwo facing electrodes, preferably at least one of which is located on aside of the membrane 5 a not exposed to the fluid.

In various embodiments, the sensor body 5 is monolithic, preferentiallymade of a ceramic material (e.g., alumina) so as to define a blindcavity, having a peripheral surface and a bottom surface, with thelatter that belongs to the membrane 5 a (in particular, to the innerside of the latter). In various preferred embodiments, the blind cavityof the sensor body 5 has an intermediate narrowing or variation ofsection so as to define a lower cavity portion C′, which is wider, andan upper cavity portion C″, which is narrower. An embodiment of thissort proves particularly advantageous in so far as it enables areduction of the area of the deformable membrane 5 a, which in this caseprovides the bottom of the narrower cavity portion C″ and to which acorresponding element 6 for detecting deformation is in any caseassociated, in particular in order to withstand higher pressures orthrusts.

In various embodiments, present within the space defined by the casing2-3 is a circuit that includes electrical and/or electronic componentsfor control and/or treatment and/or processing of a signal generated bythe detection element 6. In the case exemplified, the aforesaid circuit(not represented) is provided directly on the sensor body 5, on theupper face of which the aforesaid electrical and/or electroniccomponents are located. For this purpose, it will be appreciated thatthe area of the upper face of the sensor body 5 that surrounds themembrane 5 a is relatively wide and that to the aforesaid area therecorresponds a portion of the body 5 that is in any case relativelythick: in this way, in this area, at the upper face of the body 5 therecan hence be directly provided the aforesaid electrical/electroniccomponents. Alternatively, the aforesaid circuit or electrical and/orelectronic components may be provided on a board (not represented)associated, or fixed, or glued to the aforesaid sensor body 5.

In embodiments of this type, associated to the circuit provided on thesensor body 5 are contacts 10, which electrically connect electricallyconductive pads or paths of the circuit itself to respective terminals11 (just one is visible in FIG. 2) associated to the casing part 3 ofthe device 1. In various embodiments, the contacts 10 are elasticcontacts, in particular made according to the specific teachingsreferred to in WO 2009/153737 filed in the name of the presentApplicant, the contents of which are considered as being incorporatedherein. The terminals 11 have a first portion preferably configured forelectrical and mechanical coupling to a part of the contacts 10, forexample a substantially L-shaped configuration. The casing part 3defines a tubular portion 3 a—which here extends in a generally axialdirection of the device 1—within which respective second portions of theterminals 11 extend, to provide an electrical connector.

In other possible embodiments, the circuit for control, and/ortreatment, and/or processing of the signals generated by the sensingelement 6 is on the outside of the device 1, i.e., connected downstreamof the terminals 11 (e.g., integrated in an electronic control unit onboard a vehicle on which the device 1 is installed), in which case thecontacts 10 have simply the function of connecting the sensing element 6to the terminals 11. According to further possible embodiments, theaforesaid circuit comprises, instead, a circuit board of its own, setwithin the casing 2-3, possibly with a corresponding positioning elementand/or spacer, for example as described in WO2008/078184 A2.

The supporting body 2 has a hydraulic-connection portion 2 a, preferablyprojecting and having a cylindrical conformation, designed forconnection with a line in which the fluid the pressure of which is to bedetected passes. Preferentially, on the outside of thehydraulic-connection portion 2 a is provided an external sealing element13, here having an annular shape, for example an O-ring.

The opposite part of the supporting body 2, i.e., its upper face orsurface, is configured peripherally—in a way in itself known—forcoupling with the casing part 3, for example with a fluid-tight fixingobtained by welding. Branching off from the hydraulic-connection portion2 a is a through cavity, designated by 14, which extends through thebody 2, preferably in an axial direction, up to its upper face. In oneor more embodiments, the through cavity 14 defines at least in part apassageway for the fluid the pressure of which is to be detected, theaforesaid passageway being designated as a whole by 15 in FIG. 2. Aswill be seen, at least one part of the aforesaid passageway 15 isdefined by a respective compressible body, i.e., a variable-volumecompensation body, which is associated to the supporting body 2,preferably made of one or more elastically compressible and/or yieldingmaterials configured for compensating possible variations in volume ofthe fluid, in particular in the case of freezing thereof.

In preferred embodiments, one and the same compressible body is shapedso as to define a number of elastically compressible compensationelements. A non-limiting example of such a compressible or elasticallydeformable body is designated as a whole by 16 in FIG. 2. In the exampleillustrated, the body 16 defines two elements (20, 21) for compensationof possible variations of volume of the fluid, which define respectiveportions (20 a, 21 a) of the passageway 15.

The sensor body 5 is mounted on the supporting body 2 in such a way thatthe lower surface of its membrane 5 a is exposed to the fluid at outletfrom the passageway 15, in particular facing the outlet of the latter(here defined by an axial duct 21 a of the compensation element 21). Inpreferred embodiments, the device 1 further comprises an internalsealing element, designated by 17, which is set between the supportingbody 2 and the sensor body 5, so as to define with these a sensingchamber (not shown). The passageway 15 gives out into the aforesaidchamber, so that the pressure of the fluid can act on the membrane 5 a.

In one embodiment, such as the one exemplified, the supporting body 2has, at its upper face, a central projecting portion, visible also inFIGS. 3 and 5-7, where it is designated as a whole by 2 b, traversed bya respective part of the through cavity 14. The internal sealing element17 extends around the aforesaid portion 2 b, preferably at acorresponding external seat or shoulder of the portion 2 b itself: inthis way, the sealing element 17 provides a radial seal between theportion 2 b and the sensor body 5, in particular the peripheral surfaceof its blind cavity, delimiting with the aforesaid elements the abovesensing chamber.

In preferred embodiments, such as the one illustrated in FIG. 2, thecompressible body 16 defines at least two different compensationelements 20 and 21, here also defined as “internal” and “external” orelse “first” and “second”, respectively. The aforesaid terms, “internal”and “external”, refer to arrangements of the compensation elements 20and 21 that have been represented and/or are preferential, where thecompensation elements are located prevalently or at least in part on theinside and on the outside, respectively, of the body 2; these terms areused herein merely for convenience.

The body 16, i.e., each of the compressible bodies 20 and 21, ispreferentially made of a polymer or an elastomer, preferably a siliconematerial, such as a silicone elastomer or a liquid silicone rubber (LSR)or fluoro liquid silicone rubber (FLSR), preferably a bicomponentmaterial or a bicomponent silicone, in particular of the type designedto be overmoulded or co-moulded via injection.

The internal compensation element 20, which extends at least in partwithin the through cavity 14, has a preferably generally cylindricaland/or frustoconical shape, or a tubular or annular shape. The element20 delimits at least one respective part of the passageway 15: for thispurpose, in various embodiments, the element 20 has at least one duct,which extends in an axial direction, such as the duct designated by 20a; as will be seen, on the other hand, according to other embodiments,the element 20 may be shaped for delimiting a duct for the fluidtogether with a surface or wall of the supporting body 2.

The external compensation element 21 is set, instead, in a positiongenerally facing the membrane 5 a of the sensor body 5 and extends atleast in part on the outside of the through cavity 14, in particular atthe top of the projecting portion 2 b of the supporting body 2, in aposition relatively close to the membrane itself. Also the externalcompensation element 21 preferably delimits at least one respective partof the passageway 15. For this purpose, in various embodiments, theelement 21 is provided with a through duct, which extends in an axialdirection, designated by 21 a and preferably forms a terminal stretch ofthe passageway 15 (not, however, excluded from the scope of theinvention is the presence of a projection or a terminal tubular insertof the portion 2 b, surrounded by the element 21, as in WO2008/078184).

As may be noted in FIG. 2, the external compensation element 21 ispreferentially located within the blind cavity of the sensor body 5,with part of its peripheral surface relatively close to a correspondingpart of the peripheral surface of the aforesaid blind cavity, and withits upper surface relatively close to the lower surface of the membrane5 a.

The preferential use of a sensor body 5 with two cavity portions C′ andC″ having a different cross section enables provision of a wider lowercavity portion C′, in which it is possible to obtain more convenientlyan internal radial seal, via the sealing element 17, and provision of amore restricted upper cavity portion C″, which is able to contain asmaller amount of fluid and is hence subject to lower mechanicalstresses in the event of freezing and/or expansion of the fluid. In thisway, freezing of the smaller amount of fluid that can be contained inthe cavity portion C″ may be more conveniently compensated by theelement 21. For this purpose, in embodiments of the type exemplified inFIG. 2, it is preferable for the external compensation element 21 toextend at least in part within the upper portion C″ of the blind cavityof the body 5 so as to reduce further the volume that can be occupied bythe fluid.

The supporting body 2 has a first body portion, which is shaped so as todefine at least one first passage of the through cavity 14, inparticular a passage defining a narrowing of the through cavity itself,where the compensation elements 20 and 21 are located upstream anddownstream of the aforesaid portion, respectively. The aforementionedfirst body portion, designated as a whole by 2 c, comprises a transversewall 22 of the through cavity 14, which is in a position relativelyclose to the sensitive component 5, in particular in the proximity ofthe upper end of the through cavity 14 opposite to thehydraulic-connection portion 2 a. In various embodiments, the first bodyportion 2 c is located in an intermediate position of the projectingpart 2 b of the body 2. Preferably, the upper end of the element 20 isin contact with the lower side of the wall 22, whereas the base end ofthe element 21 is in contact with the upper side of the wall 22.

As may be appreciated also in FIG. 3, the transverse wall 22 istraversed by at least one respective first passage that forms arespective part of the passageway 15 and includes at least onerespective inlet 23 a for the fluid and at least one respective outlet23 b for the fluid. It should be noted that the terms “inlet” and“outlet” are used for convenience in so far as they may refer, forexample, to the albeit minimal displacements of the fluid that occur inthe device in order to transfer the corresponding pressure towards thesensing membrane; in practical use, in fact, the fluid inside the deviceis substantially in static conditions.

In various preferred embodiments, the at least one inlet 23 a and the atleast one outlet 23 b of the aforesaid first passage have relativepositions such that the fluid undergoing measurement is prevalentlyinduced to follow a tortuous path, at the area of the wall 22. For thispurpose, in various preferred embodiments, the at least one inlet 23 aand the at least one outlet 23 b are staggered with respect to oneanother.

In various embodiments, such as the one represented in FIG. 2, the inlet23 a and the outlet 23 b extend according to respective axes that aresubstantially parallel to one another. For this purpose, in preferredembodiments, the inlet 23 a and the outlet 23 b are substantially formedby two cavities, each with a respective bottom wall, defined at oppositesides of the transverse wall 22, which open downwards and upwards,respectively. The aforesaid cavities, preferably substantiallycylindrical or with a profile that is at least in part curved, arearranged so as to intersect in a lateral direction in order to be influid communication with one another and thereby define the aforesaidsubstantially tortuous path for the fluid. The aforesaid cavities willbe defined hereinafter for simplicity also as “blind cavities”.

An embodiment of this sort proves particularly advantageous when thesupporting body 2 is made of a single piece of moulded plastic material,in particular injection moulded material (albeit possibly being made ofanother material, such as a metal stamped or machined using a machinetool). For this purpose, the body 2 is preferably made of a polymer or acopolymer or a thermoplastic material, such as a polyamide PA or apolyphthalamide PPA or a mixture or combination of both (PA and PPA).The supporting body 2, albeit made of a polymer, preferably has astructure and/or parts with a thickness and/or shape such as to besubstantially rigid and/or able to withstand mechanical thrusts and/orstresses, such as mechanical thrusts and/or stresses due to a pressureand/or an expansion of the fluid contained in the device.

The fact that the passage 23 a-23 b that traverses the transverse wall22 is obtained by two blind cavities that open in opposite directionsand that intersect one another prevents the presence of undercuts orrecesses, and hence considerably simplifies moulding of the body 2 andthe corresponding equipment.

In various embodiments, such as the one exemplified so far, the outlet23 b is in a substantially central position of the transverse wall 22,i.e., substantially coaxial to the through cavity 14 as a whole: in thisway, the through duct 21 a of the compensation element 21—which hereconstitutes a terminal stretch of the passageway 15—may be defined in asubstantially central position of the element 21 itself and may directlyface the central area of the membrane 5 a of the sensitive element. Onthe other side, instead, the inlet 23 a is in an eccentric position withrespect to the outlet 23 b, and for this purpose the axial duct 20 a ofthe compensation element 20 is shifted with respect to the axis of theelement itself. Hence, as may be appreciated, in the embodimentexemplified in FIG. 2, the inlet 23 a is in fluid communication with theoutlet end of the through duct 20 a of the compensation element 20,whereas the outlet 23 b is in fluid communication with the inlet end ofthe through duct 21 a of the compensation element 21, the two ducts 20 aand 21 a being staggered with respect to one another.

In operation of the device 1, the fluid undergoing measurement reachesthe inside of the device 1 through the hydraulic-connection portion 2 a,from which the through cavity 14 of the supporting body 2 branches off.The fluid thus occupies the duct 20 a of the compensation element 20,the passage 22 a-22 b defined in the transverse wall 22, and the duct 21a of the compensation element 21.

In this way, the fluid occupies the sensing chamber defined between thetop of the projecting part 2 b of the body 2, the sealing element 17 andthe inner surfaces of the cavities C′-C″. The pressure of the fluid inthe aforesaid chamber determines bending or elastic deformation of themembrane 5 a of the sensitive element, the extent of which is detectedby the detection element 6. The electrical signal determined by theaforesaid detection element 6 represents the pressure of the fluid,according to a technique in itself known.

In the event of freezing of the fluid contained within theaforementioned sensing chamber, ducts 20 a, 21 a, and passage 23 a-23 b,there occurs an expansion or increase in volume of the fluid itself,which is compensated prevalently by the deformation of the elements 20and 21 and in part by the deformation of the sealing element 17. Invarious preferred embodiments, the presence of the tortuous pathdetermined by the mutually staggered positions of the inlet 23 a and ofthe outlet 23 b of the intermediate wall 22 prevents the increase involume in an axial direction of the icy fluid contained in thepassageway 15 from exerting a significant thrust on the membrane 5 a ofthe sensitive element 5. For this purpose, it should be considered thatthe length of the duct 21 a is preferably shorter than the length of theduct 20 a, the former being in particular less than half of the second.

The increase in volume in an axial direction is hence greater for thefluid contained in the duct 20 a of the element 20 and in the inlet 23a, which constitute a preponderant part of the passageway 15 of thefluid. However, the axial increase in volume of this part of the fluidis countered upwards by the bottom of the blind cavity that forms theinlet 23 a. Instead, the increase in volume in an axial direction of thefluid contained in the outlet 23 b and in the duct 21 a of the element21 is more limited, given that these constitute a lesser part of thepassageway 15. In this way, then, the thrust upwards determined by theincrease in volume of the icy fluid within the outlet 23 b and the duct21 a is modest and such as not to determine risks of failure of themembrane 5 a.

In various embodiments, notwithstanding the staggered arrangement of theinlet and outlet, the passage 23 a-23 b in any case includes an albeitminimal axial stretch—represented dashed in FIG. 7—determined by theintersection of the two cavities that provide the aforesaid inlet andoutlet. The cross-sectional dimension of the aforesaid axial stretch isin any case very limited and such as not to affect appreciably thefunction of protection just described above, in particular being such asnot to allow any displacement or extrusion towards the membrane 5 a of apossible column of icy fluid in the duct 20 a.

In preferred embodiments of the invention, the single deformable body 16that forms the compensation elements 20 and 21 is a body overmoulded onthe supporting body 2, or co-moulded therewith. More in general, inaccordance with the invention, the body 16 is an overmoulded orco-moulded element having respective opposite portions that extend atopposite sides of the transverse wall 22, where the aforesaid oppositeportions—here exemplified by the elements 20 and 21—are connectedtogether by means of at least one intermediate portion.

It is pointed out that, in the present description and in the attachedclaims, and where not otherwise specified, the generic term“overmoulding” and its derivatives are to be understood as designatingat least two different moulding techniques, and especially the techniqueof overmoulding in a strict sense and the technique of co-moulding. Inovermoulding in a strict sense, a first component previously obtained(e.g., the supporting body 2) is inserted in a mould, where there isthen injected in the molten or liquid state at least one materialdesigned to provide a second component (e.g., the compressible body 16)on the first component. Instead, in co-moulding, in a particular mouldthere is first injected in the molten or liquid state at least onematerial designed to form the first component, after which a part of themould is replaced—frequently in an automatic way—with a different part,and, in the new mould thus formed, still housing the first component, atleast one material is injected in the molten or liquid state to form thesecond component on the first component (alternatively, the aforesaidpart of the mould may be turned over, instead of replaced, in such a waythat a different portion thereof forms part of the moulding impression).

In practice, then, in the first case the first component is obtainedapart, introduced into the mould, and moulded thereon is the secondcomponent, possibly with the use of an adhesion promoter (primer)distributed over at least part of the first component, whereas in thesecond case both components are obtained, one after another, in at leastpart of one and the same moulding equipment, preferably overmoulding thesecond component soon after, in particular after a few tens of secondsor a few seconds, when the first component is still hot or has not yetreached room temperature. In this way, also obtained are preferablystructural or chemical bonds and/or a better adhesion between the firstand second components. In either case, however, one component is mouldedon the other. Exemplified in the present description is the case ofovermoulding of a first component (such as a compressible body) on asecond component (such as a housing or supporting body), but theinvention may be equally applied to the case of co-moulding of the twocomponents in question (including the case of overmoulding orco-moulding of a housing or supporting body on or with a compressiblebody).

In the embodiments in which the elements 20 and 21 are made of a singlepiece, in particular a single overmoulded compensation element, thecorresponding body 16 has at least one intermediate portion, whichconnects together the first and second compressible elements 20 and 21.In FIG. 2, one of the aforesaid connection portions is designated by 16a. In the aforesaid embodiments, the portion 2 c of the supporting body2, in particular the transverse part 22, is shaped so as to define atleast one second passage, and the at least one connection portion 16 aof the compressible body 16 extends through the aforesaid secondpassage. Preferentially, the at least one second passage determines arespective restriction in cross section of the through cavity 14.

In various embodiments, the transverse wall 22 of the body 2 is thusprovided with one or more second passages, in addition to the passage 23a-23 b. Some of the aforesaid second passages are designated by 24 inFIGS. 3 and 4-6 and are preferentially located in a position peripheralor eccentric with respect to the duct portion 23 a-23 b of the fluid.Preferentially, a plurality of second passages 24 is provided, arrangedaround the inlet 23 a and the outlet 23 b of the intermediate wall 22.In various embodiments, the second passages 24 are arranged according toa circumference or an arc of circumference. Preferentially, the secondpassages 24 have a cross section or profile at least in part curved orrounded, not necessarily circular.

According to the invention, the body portion 2 c is moreover shaped soas to define at least one detent means, such as a step, or a projection,or a radial or transverse relief, designed to counter possible phenomenaof displacement or extrusion of the material that forms the compressiblebody 16 as a result of the pressure of the fluid undergoing detection.For this purpose, in various embodiments, the body portion 2 c comprisesat least one projecting wall, which is defined downstream of thetransverse wall 22 and extends towards the inside of the through cavity14. Preferably, the aforesaid projecting wall overlies at leastpartially a corresponding second passage 24, or each second passage 24,as may be evinced, for example from FIGS. 3, 5, and 6, where theprojecting wall is designated by 25. The projecting wall 25 ispre-arranged for determining a narrowing or a variation of acorresponding second passage 24, or of each second passage 24, inparticular so as to define a corresponding reduction in cross section ora tortuous path of the corresponding intermediate portion 16 a of thecompressible body 16. This characteristic may in particular beappreciated in FIG. 7. As may be noted, the second passages 24 areprevalently occupied by respective parts 16 a ₁ of the material of theconnection portions 16 a of the compressible body 16.

The presence of the projecting wall 25 that overlies the second passages24 provides a step that determines a narrowing of the upper section ofthe passages 16 a themselves, this narrowing being occupied by a minimumsection 16 a ₂ of the material of the connection portions 16 a. A part16 a ₃ of the material of the connection portions 16 a—which forms inpart also a sort of base of the compressible element 21—occupies,instead, the area circumscribed by the projecting wall 25. The part 16 a₁ and the part 16 a ₃ are preferably staggered radially or laterallywith respect to one another.

Partially visible in FIGS. 8 and 9 is an example of deformable body 16that defines the compensation element 20 and the compensation element21, where the parts 16 a ₁ and 16 a ₃ of the material of the connectionportions 16 a are highlighted. The aforesaid parts 16 a ₁, 16 a ₂, and16 a ₃ are moreover visible in the cross-sectional views appearing inFIGS. 11-13.

An arrangement of the type described enables effective limitation of theeffects of a possible extrusion or displacement of the material thatforms the single body 16 due to the pressure of the fluid at inlet, asexplained in the introductory part of the present description. Thiseffect is obtained both thanks to the fact that the lower surface of theprojecting wall 25 opposes extrusion upwards of the materialconstituting the body 16 and because the section of effective passage ofthe material of the body 16, here represented by the parts designatedwith 16 a ₂, is minimal.

In various preferred embodiments, the transverse wall 22 of the body 2is an intermediate wall of the through cavity 14, i.e., a wall that isin an intermediate position at the two ends of the through cavity 14,but preferably in a position closer to the end of the through cavityfacing the sensitive element. In embodiments of this type, the throughcavity 14 or the body portion 2 b can be advantageously shaped so as todefine, beyond the transverse wall 22, a portion for housing thecompressible element 21, clearly visible for example in FIGS. 3, 5, and6, where the aforesaid housing portion is designated by 26, inparticular a hollow cylindrical portion. As may be noted, the housingportion 26 is basically located at the top of the projecting portion 2b.

With reference also to FIG. 7, it may be clearly noted how a lower partof the element 21—designated by 21 ₁—is located within the aforesaidportion 26, whereas an upper part of the element 21—designated by 21₂—is located on the outside of the aforesaid housing portion 26, i.e.,within the blind cavity of the pressure-sensitive element.

Preferably, in the operating conditions, in the event of freezing of thefluid contained at least in the upper cavity portion C″ of the body 5 ofthe sensitive element, the aforesaid lower part 21 ₁ of the element 21is constrained peripherally by the portion 26, in particular in order toprevent any radial deformation and/or to provide a better support orfixing of the upper part 21 ₂ of the element 21. The upper part 21 ₂ ofthe compensation element 21 can, instead, undergo compression ordeformation according to different angles (e.g., either radially oraxially), in order to compensate freezing and/or expansion of the fluidcontained at least in part in the upper cavity portion C″.

Preferably, the upper part 21 ₂ of the compensation element 21 extendsat least in part also in the lower cavity portion C′ in order tocompensate also freezing or expansion of the fluid contained in a partof the aforesaid lower portion C′, in the area delimited also by thesealing element 17.

From FIG. 3 it may be noted how, in preferred embodiments, the throughcavity 14 that traverses the supporting body 2 presents an intermediatenarrowing or restriction also in its area that is to house thecompressible element 20, this intermediate narrowing being designated by14 a only in FIG. 3: in this way, also the compensation element 20 hastwo stretches of different diameter, or in any case with differentcross-sectional dimensions, preferably having at least one step thatopposes extrusion or displacement of the compensation element 20 towardsthe membrane 5 a.

This solution, together with the fact that the element 21 is positionedbeyond the transverse wall 22 but connected or fixed with respect to theelement 20, guarantees positioning and/or fixing of the deformable body16 as a whole both in the case of high pressures of the fluid and in thecase of violent negative pressures of the fluid or of possible looseningof the material or materials constituting the deformable body 16. Ofcourse, the narrowing 14 a proves useful also for the purposes ofcountering the aforementioned phenomena of extrusion of the material ofthe body 16 towards the membrane 5 a.

In various autonomously inventive embodiments, i.e., even in the absenceof a transverse wall of the type designated by 22, the through cavity 14of the body 2 has a peripheral surface shaped so as to define one ormore reliefs that perform the function of retention of the at least onecompressible element.

With reference, for example, to FIGS. 3, 4, and 7, designated by 27 areprojecting annular reliefs of the peripheral surface of the throughcavity 14, which may be provided in the part of the duct 14 that housesthe compressible element 20 and/or in the part of the through cavity 14that partially houses the compressible element 21, i.e., in the housingportion 26. As may be noted in particular in FIG. 7, these reliefs 27are preferentially not very accentuated and have markedly flaredradiusing surfaces so as to prevent the presence of undercuts that mighthinder extraction of the body 2 from the corresponding manufacturingmould, when the aforesaid body 2 is obtained via moulding of plasticmaterial. The reliefs 27 perform, as has been said, a function ofretention of the elements 20 and/or 21, or of the single body 16 thatconstitutes them, for the purposes of countering the aforementionedphenomena of extrusion or displacement.

Represented schematically in FIGS. 14-17 is possible moulding equipmentthat can be used for overmoulding a deformable body 16 on a supportingbody 2, for a device 1 of the type described previously with referenceto FIGS. 1-13.

With initial reference to FIG. 14, in the example the equipmentcomprises two mould parts 30 and 31. In the example, the mould parts 30and 31 each define an impression 30 a and 31 a for positioning of thesupporting body 2, previously obtained, as well as for definition ofsome internal and external profiles of the deformable body 16. Inparticular, the impression 30 a includes a central base part 30 a ₁necessary for definition of the lower face of the body 16, from whichthere projects a columnar element 30 a ₂ shaped so as to define theaxial duct 20 a of the element 20. On the other side, the impression 31a includes a central part 31 a ₁ necessary for definition of theexternal profile of the portion 21 ₂ (see FIGS. 8-9) of the compressibleelement 21, from which there projects a columnar element 31 a ₂ shapedso as to define the axial duct 21 a of the element 21.

In FIG. 15, the equipment is represented in a condition where the mouldis still open, after the body 2 previously formed has been positionedtherein. After closing of the mould and start of injection of thematerial in the molten state, the latter occupies the free spacesdefined between the parts 30, 31 and the body 2 (including the passages24 of the body 2) so as to obtain the compressible body 16. It willhence be appreciated that, in an application of this type, one and thesame supporting body 2 is to constitute a sort of “part of mould”necessary for definition of the final shape of the compressible body 16.After the necessary period of cooling and solidification of theovermoulded material, the mould parts 30 and 31 may be separated, asillustrated schematically in FIG. 16, with the body 16 by now formed onthe body 2.

From the detail of FIG. 17—where the mould is represented in a closedcondition, with the body 2 inside it and prior to injection of thematerial—it may be appreciated how the columnar elements 30 a ₂ and 31 a₂ are in positions staggered in a lateral direction, in particulararranged so that the corresponding free ends obstruct the inlet 23 a andthe outlet 23 b of the transverse wall 22, respectively, so as toprevent the material in the molten state from possibly penetrating intothe aforesaid inlet and outlet.

FIG. 18 illustrates, in a view similar to that of FIG. 2, a variantembodiment according to which the axial duct 20 a of the compressibleelement 20 extends in an axially central position of the element itself,i.e., in a position substantially coaxial with respect to the cavity 21a of the compensation element 21 and the outlet 23 b defined in thetransverse wall 22. The only substantial difference from the embodimentillustrated in FIGS. 1-13 is hence represented by the fact that thecross-sectional dimension or diameter of the duct 20 a is greater thanin the previous case so that the aforesaid duct is in a central positionand in any case faces the inlet 23 a of the transverse wall 22. For therest, production and operation of the device 1 of FIG. 18 are similar tothose already described above.

FIGS. 19-28 illustrate, in views similar to those of FIGS. 2, 3, 6, 4,5, 8, and 10-13, respectively, a further embodiment of a deviceaccording to the invention. In this case, the portion 2 c of the body 2is shaped so as to define at least one step (or radial or transverseprojection or relief) at a lower end region of a second passage 24, orof each second passage 24. More in particular, in the case illustrated,the portion 2 c of the body 2 is shaped so as to define at least twosteps or projections or reliefs in opposite end regions of a secondpassage 24, or of each second passage 24.

The characteristic in question may be appreciated in particular fromFIGS. 20 and 21, where it may be noted how the transverse wall 22 isshaped so as to define—at the bottom end of a respective second passage24—a respective step (or projection, or relief) designated by 28,projecting towards the inside of the second passage itself.

Advantageously, the extent (dimension) of projection of the steps 28 andthe extent (dimension) of projection of the steps or reliefs determinedby the projecting wall 25 are chosen so as to prevent the presence ofundercuts, as intuitively highlighted by the dashed lines of FIG. 20.This simplifies considerably the production of the body 2 when this ismade of a single piece of moulded plastic material, with evidentadvantages also in relation to simplification of the moulding equipment.

As may be seen in FIGS. 24-28, the presence of the steps 28 and of theprojecting wall 25 enables in practice determination of the presence oftwo restrictions in section of the second passages 24, at their twoends, thereby bestowing upon the connection portions 16 a of thecompressible body 16 a substantially tortuous development, in particularcomprising a number of stretches substantially staggered or angled withrespect to one another.

As may be appreciated in particular from FIGS. 24 and 25, the steps 28enable definition of reduced sections 16 a ₄ of each of the portions 16a also at their area of connection to the compressible element 20. Theaforesaid reduced sections 16 a ₄ preferably have dimensions larger thanthe reduced sections 16 a ₂ determined by the projecting wall 25 (seeFIGS. 26 and 28), but enable further reduction of the risks derivingfrom possible extrusion of the material constituting the compressiblebody 16.

Production and operation of the device 1 of FIGS. 19-28 are similar towhat has already been described above.

FIGS. 29-35 illustrate, in views similar to those of FIGS. 1-6, afurther embodiment of a device according to the invention. In this case,the first passage for the fluid that traverses the transverse wall 22has two generally parallel inlets 23 a, in fluid communication with oneand the same outlet 23 b, which is staggered with respect to the twoinlets 23 a.

Preferentially, the two inlets 23 a are formed by two blind cavities(i.e., with a respective bottom), which are defined at the lower side ofthe wall 22, open downwards, and are substantially parallel to oneanother, preferably symmetrical with respect to the axis of the deviceand/or of the outlet 23 b. The outlet 23 b is formed by a blind cavitydefined at the upper side of the wall 22, which opens upwards. Theaforesaid three cavities are preferably substantially cylindrical or asection at least in part curved and, very preferably, their axes aresubstantially parallel to one another. Preferably, the sum of thesections of passage of the two inlet stretches 23 a is equal or close tothe section of the outlet stretch 23 b.

The two inlets 23 a are arranged so as to intersect the outlet 23 b in alateral direction in order to be in fluid communication therewith andthus define a substantially tortuous path for the fluid. Solutions ofthis type enable reduction of the risks deriving from the increase involume of the fluid in an axial direction, in the case of freezing, asexplained previously. In these embodiments, the staggered arrangementbetween the inlets and the outlet in any case determines the presence,in the duct portion 23 a-23 b of the through cavity 14, of two parallelaxial stretches, determined by the intersections of each inlet with theoutlet.

Advantageously, the cross-sectional dimensions of the aforesaid twoaxial stretches may each be smaller than the single axial stretchpresent in the case of the embodiments described previously, inparticular in order to have a smaller volume and hence a smallerexpansion and/or a lower thrust by the icy fluid in the direction of themembrane, thereby increasing the function of protection in regard to themembrane of the sensitive element.

In embodiments of this type, the internal compressible element 20 may beshaped so as to present two mutually parallel through ducts 20 a, asrepresented in FIG. 30, the outlet ends of which are in fluidcommunication with the two inlets 23 a. On the other hand, the externalcompressible element 21 may have a structure similar to those describedpreviously, and hence with the inlet end of the corresponding throughduct 21 a in fluid communication with the outlet 23 b. Of course,instead of two axial ducts 20 a, the internal compressible element 20may be provided with a single axial duct 20 a, having increasedcross-sectional dimensions, or in any case dimensions such that both ofthe inlets 23 a of the transverse wall 22 face its outlet end. Such acase is exemplified in FIG. 36, where, albeit in the presence of alarger section of the duct 20 a, the possible thrust due to the icyfluid is countered by the lower part without passages of the transversewall 22, which opposes expansion and thrust in the direction of themembrane of the icy fluid in the duct 20 a.

Preferably, the sum of the cross-sectional dimensions of the aforesaidaxial stretches is equal to or greater than the size of the single axialstretch present in the case of the embodiments described previously.Preferably, moreover, the sum of the sections of passage of the twoinlets 23 a and/or of the corresponding ducts 20 a is equal to orgreater than the cross section of the outlet 23 b and/or of thecorresponding duct 21 a.

For the rest, production and operation of the devices 1 of FIGS. 29-35and 36, respectively, are similar to the ones already described above.

FIGS. 37-41 illustrate, in views similar to those of FIGS. 2-6, afurther embodiment of a device according to the invention. In this case,the first passage for the fluid that traverses the transverse wall 22has two generally parallel outlets 23 b, in fluid communication with oneand the same inlet 23 a, which is staggered with respect to the twooutlets 23 b.

Preferentially, the two outlets 23 b are formed by two blind cavities,which are defined at the upper side of the wall 22, open upwards, andare substantially parallel to one another. The inlet 23 a is formed by ablind cavity defined at the lower side of the wall 22, which opensdownwards. Also in this case, the aforesaid three cavities arepreferably substantially cylindrical or at least in part curved and,very preferably, their axes are substantially parallel to one another.

The two outlets 23 b are arranged so as to intersect in a lateraldirection the inlet 23 a in order to be in fluid communication therewithand define the substantially tortuous path for the fluid. Solutions ofthis type afford substantially the same advantages described withreference to the embodiments of FIGS. 29-35.

In embodiments of this type, the external compressible element 21 may beshaped so as to present two mutually parallel through ducts 21 a, asrepresented in FIG. 37, the inlet ends of which are in fluidcommunication with the two outlets 23 b. On the other side, the internalcompressible element 20 may have a structure similar to those describedpreviously, and hence with the outlet end of the corresponding throughduct 20 a in fluid communication with the inlet 23 a. Of course, insteadof two axial ducts 21 a, the external compressible element 21 may beprovided with a single axial duct 21 a, having increased cross-sectionaldimensions, or in any case dimensions such that both of the outlets 23 bof the transverse wall 22 face its inlet end. Such a case is exemplifiedin FIG. 42, where preferably the section and/or height of the axial duct21 a is predefined so as to limit linear expansion of the icy fluid andprevent of damage to the membrane.

For the rest, production and operation of the devices 1 of FIGS. 37-41and 42, respectively, are similar to what has already been describedabove.

It will be appreciated, with reference to the embodiments of FIGS. 29-35and 37-41, that the first passage for the fluid that traverses thetransverse wall 22 could have more than two inlets 23 a in fluidcommunication with at least one outlet 23 a (in which case also theelement 20 could have a number of ducts corresponding to the number ofinlets 23 a) or else more than two outlets 23 b in fluid communicationwith at least one inlet 23 a (in which case also the element 21 couldhave a number of ducts corresponding to the number of inlets 23 a).

FIGS. 43-54 illustrate, in views similar to those of FIGS. 2, 3, 6, 4,5, 8, 9 and 10-13, a further embodiment of a device according to theinvention.

In this case, the first portion 2 c of the body 2 is without aprojecting annular wall (of the type previously designated by 25) butthe second passages of the transverse wall 22, which are to receivethrough them the connection portions 16 a of the compressible body 16,are in any case shaped so as to define a tortuous path.

In embodiments of this type, the second passages may advantageously beobtained using the same technique employed for providing the inlet 23 aand the outlet 23 b of the transverse wall 22, for example as describedwith reference to FIGS. 1-7.

In various embodiments, and as may be appreciated in particular fromFIGS. 44 and 45, each second passage includes two blind cavities 24 aand 24 b (i.e., with respective bottom) staggered with respect to oneanother, with the respective axes that are preferably substantiallyparallel to one another. The two cavities 24 a and 24 b are defined atopposite sides of the transverse wall 22, and hence open downwards andupwards, respectively. The aforesaid blind cavities, which are notnecessarily cylindrical, are arranged so as to intersect in a lateraldirection in order to be connected directly together. As may beappreciated, also this embodiment proves advantageous when thesupporting body 2 is made of a single piece of moulded plastic material,given the absence of undercuts or recesses.

The second passages 24 a-24 b thus obtained determine a development ofthe corresponding connection portion 16 a of the body 16 that comprisesa tortuous path or a number of stretches angled with respect to oneanother.

This characteristic may be particularly appreciated from FIGS. 48-50,where it may be noted how the connection portions 16 a basically includetwo axial stretches 16 a ₅ and 16 a ₆ that are substantially parallel,but joined together in an intermediate area 16 a ₇ (it may be noted howin FIGS. 48-50 the corresponding planes of section are staggered withrespect to the axes of the body 16 and of the body 2). The structure ofthe passages 24 a-24 b and of the corresponding intermediate portions ofthe body 16 may be appreciated also in the sections presented in FIGS.51-54.

As has been said, in various embodiments, the cavities provided with abottom that constitute the at least one inlet 23 a and the at least oneoutlet 23 b of the transverse wall 22 are staggered with respect to oneanother, but intersect laterally, thereby defining prevalently lateralcommunication passages, which enable passage of the fluid that is beingmeasured between the two cavities in question. Preferentially, theaforesaid lateral passages have cross-sectional dimensions close to orlarger than the cross-sectional dimensions of each of the staggeredcavities, in particular in order to guarantee an appropriate lateralsection of passage for the fluid, such as a section that will not causeany choking in regard to the sections of passage of the staggeredcavities and/or in regard to the entire path. Similar considerationsapply to the passages that are to house the material of the connectionportions 16 a, in particular when also these passages are defined bystaggered cavities of the type designated by 24 a and 24 b.

As may be evinced, also embodiments of this type enable a considerablereduction of the aforesaid risks deriving from possible extrusions ordisplacements of the material constituting the compressible body 16.

The invention may be applied also to the case of pressure-sensor deviceswherein the transverse wall 22 includes a passage 23 for the fluid in aposition generally coaxial to the ducts 20 a and 21 a of thecompensation element 20 and 21, respectively, as exemplified in FIG. 55.In said FIG. 55 the passages for the connection portions 16 a of thesingle body 16 have steps at both end regions, and in particular anupper step defined by the projecting wall 25 and a lower step defined bya transverse, or radial, relief or projection at the lower end of saidpassage. Clearly, in accordance with embodiments not represented herein,the presence is not ruled out of a single step, preferably the stepdefined by the projecting wall 25.

On the other hand, only one compensation element, for example theexternal element 21, could be overmoulded on the body 2, as exemplifiedin FIGS. 56 and 57. As may be noted, in this case, it is preferable forat least a part 20′ of the overmoulded material to extend also at theside of the transverse wall 22 that is opposite to that from which thecompressible element (here the element 21) extends, so as to improveanchorage to the body 2. For this reason, it is, however, convenient toenvisage passages such as the ones designated previously by 24 or 24a-24 b. In the case of FIG. 55 the wall 22 defines a passage 23 axiallyaligned with the through ducts 20 a and 21 a of the compressibleelements 20 and 21, whereas in the case of FIG. 57 the wall 22 has apassage defined by two cavities with bottom 23 a, 23 b which arestaggered with respect to one another, as in previously describedembodiments.

As mentioned previously, instead of a projecting wall 25, thecorresponding step may be defined by a corresponding narrowing orreduction of the section of the through cavity 14 downstream of thetransverse wall 22. An embodiment of this sort is exemplified in FIG.58, where the aforesaid reduction in section, i.e., the correspondingstep, is designated by 25′. Also in this case, the step 25′ overlies thesecond passages 24 and is sized so as to prevent the presence ofundercuts, as described above with reference to the projecting wall 25.Also in the embodiments of FIGS. 55-58, at the lower end of at least onesecond passage 24, a respective step (or projection or relief) ispresent, designated by 28, which projects towards the inside of thesecond passage itself. In various embodiments, such as the embodimentsof FIGS. 55-58, at least one first step or relief 25, 25′ is present,staggered and opposite with respect to at least one second step orrelief 28, set towards the inside of the second passage 24, and/or atleast one inlet 23 a and at least one outlet 23 b are present, which arestaggered and parallel to one another and intersect laterally.

In FIGS. 1-58, the invention has been exemplified with reference todevices that use a sensitive element shaped so as to define a sensorbody made of a single piece and/or having a blind cavity, the bottom ofwhich is formed by a membrane part associated to which is at least onesensing element. The invention may in any case be used also in devicesprovided with a sensitive element of different conformation, for examplehaving a sensor body made up of a number of parts and/or having a cavitydefined by a main sensor body associated to which is a membrane partconfigured as distinct element delimiting a respective part of a cavity.

FIG. 59 exemplifies an embodiment in which the sensitive component has abody consisting of two parts, comprising a membrane 5 a, configured asdistinct component, which is rigidly fixed to a main body 5 b. In theexample, the membrane 5 a is fixed at a substantially plane end face ofthe body 5 b, here the lower face, via an annular layer of a suitableadhesive material 5 c, of a conception in itself known. In this way,defined between the body 5 b, the layer of adhesive 5 c, and themembrane 5 a is a cavity C delimited both peripherally and at the twoaxial ends. Preferably, the part 5 b of the body of the sensor ismonolithic and/or substantially rigid, and the part 5 a is at least inpart flexible. In alternative embodiments, the lower face of the body 5b may present a respective recess, which delimits part of the cavity C,for example as described in WO 2010/134043, the teachings of which areconsidered as being incorporated herein; in such cases, the membrane maybe welded to the body part 5 b, or else a layer of adhesive 5 c thinnerthan the one exemplified may be used.

The cavity C may be closed, as in the example illustrated, and sensitiveelements having this configuration are used for the production ofpressure sensors of an absolute type (in which case, in the closedcavity C a known positive or negative pressure, or else vacuum ispresent). In other embodiments, the cavity C may be in fluidcommunication with the environment via a small hole defined in the bodypart 5 b.

In these configurations, the body of the sensitive element henceincludes at least two body parts 5 a, 5 b glued or welded or renderedfixed with respect to one another, provided between which is the cavityC. In the sensitive elements of this type, the depth of the cavity C(whether this be defined by a small cavity of the body 5 a or determinedby the thickness of the annular layer 5 c for gluing of the membrane 5a) is generally modest so that the thickness of the body part 5 b on theside opposite to the membrane 5 a may be such as to enable directmounting of control and/or calibration and/or processing electricaland/or electronic components. The deformation-detection element 6 may beat least in part associated to the inner side of the membrane 5 a, andhence in a position protected from the fluid. As in previousembodiments, also in this case, elastic contacts 10 may be used, whichextend between portions of the terminals 11 and corresponding conductivepads or paths provided on the upper face of the body part 5 b.

In various embodiments of this type, a sealing element 17 is set betweenthe upper face of the supporting body 2 and the membrane 5 a (orpossibly between the upper face of the body 2 and the lower face of thebody 5 b, in the case of a membrane 5 a having a diameter smaller thanin the case of the example illustrated) so as to provide both an elasticsupport for the sensitive element and a seal of an axial type, betweenthe aforesaid upper face of the body 2 and the membrane 5 a. In variousembodiments, the sealing element 17 circumscribes an area within whichthe external compensation element 21 is located.

The compensation element 21, in various embodiments of this type,constitutes a sort of disk or plate, the lower surface of which ispreferentially set completely resting on the upper face of the body 2.From FIG. 59 it may likewise be noted how, in various embodiments, thesealing element 17 extends—with respect to the upper face of thesupporting body 2—up to a height greater than the height of thecompensation element 21: in this way, the upper face of the supportingbody 2, the lower face of the sensitive element (here represented by themembrane 5 a) and the sealing element 17 delimit the sensing chamberwithin which the element 21 is located, in a position generally facingthe membrane 5 a and set at a distance therefrom.

It will be appreciated that, in embodiments of this type, the sealingelement 17 operates at least in part as elastic or compressiblecompensation element. Also in the solutions of the type exemplified withreference to FIG. 59, the characteristics described previously may beimplemented in relation to the passages 23 a-23 b for the fluid and/orto the passages 24 for material of at least one part of connection 16 abetween the compensation elements 20 and 21.

For instance, also in this case, the supporting body 2 a has a portion 2c distinguished by the presence of a wall 22 transverse to the throughcavity 14, which is thicker than in the case of the embodimentsillustrated in FIGS. 1-59, which here defines part of the upper face ofthe body 2 (it could, however, be in an intermediate position of thethrough cavity 14).

In the example illustrated, defined in a central area of the transversewall 22 is at least one first passage for the fluid, with thecorresponding inlet section 23 a and outlet section 23 b that can beobtained with any of the modalities described previously, in fluidcommunication with the through ducts 20 a and 21 a of the compensationelements 20 and 21, respectively. In addition and/or alternatively, inthe wall 22 there may be defined the passages 24, which are to beoccupied by the connection portions 16 a of the overmoulded compressiblebody 16; also the aforesaid passages 24 and portions 16 a can beobtained according to any one of the modalities described previously.

It will moreover be appreciated that the various characteristics and/orsolutions proposed for providing the first passages, designed for thefluid undergoing detection, and of the second passages, designed tohouse the intermediate connection portions of the compressible body 16,may be variously combined together. For instance, a structure of thewall 22 that includes steps 28, as in FIGS. 19-28, may be used in allthe embodiments described previously. Also a structure of the wall 22with the second passages formed by two blind cavities 24 a, 24 bopposite and staggered, as in FIGS. 43-45, may be used in all theembodiments described previously.

The equipment of FIGS. 14-17 has been exemplified in combination withthe embodiments of FIGS. 1-13, but it is clear that equipment of thesame type may be used—with adaptations that are evident for the personskilled in the art—for producing pressure-sensor devices of variousother embodiments described previously. Moreover, the aforesaidequipment has been described mainly in combination with processes ofovermoulding in a strict sense, but, as has been said, the invention maybe implemented also by co-moulding processes, using techniques andequipment of a conception in itself clear to the person skilled in thebranch.

From the foregoing description, the characteristics and advantages ofthe present invention emerge clearly.

It is clear that numerous variations may be made by the person skilledin the branch to the devices described by way of example, withoutthereby departing from the scope of the invention. As already mentioned,for the purposes of implementation of the aforesaid further variants,one or more of the characteristics described previously with referenceto different embodiments may be combined in any adequate way.

The compensation elements 20 and/or 21 preferentially have asubstantially cylindrical or frustoconical shape or tubular or annularshape, but this does not constitute an indispensable characteristic inso far as at least one or both of the aforesaid elements 20, 21 couldhave a prismatic or polyhedral shape, such as a shape with asubstantially triangular, or quadrangular, or pentagonal, or hexagonalcross section, and the like, possibly with rounded corners.

The duct 20 a, 21 a of one or both of the elements 20, 21 may be atleast in part delimited between a surface profile of the compressibleelement and a surface profile of the supporting body 2 (instead of beingformed by a through duct entirely defined by the compressible element).For instance, the compressible element 20 and/or 21 may have at leastone surface groove that delimits, with a respective inner surface of thethrough cavity 14, at least part of the corresponding duct, or viceversa an inner surface of the through cavity 14 of the supporting body 2may have at least one surface groove that delimits, with a respectivesurface of the compressible element 20 and/or 21, a corresponding duct,or else again both the compressible element 20 and/or 21 and the throughcavity 14 may have respective grooves facing one another or coupledtogether to form at least part of a duct and/or of the passageway 15. Anembodiment of this sort is illustrated schematically in FIG. 60: thisfigure illustrates a device 1 of the same type as the one illustrated inFIG. 59, but one or more of the characteristics described hereinaftermay be applied also to the case of devices of the type illustrated withreference to FIGS. 1-58.

In the case illustrated in FIG. 60, the device 1 includes a compressiblebody defining the compensation elements 20 and 21, provided on theperipheral surface of which are one or more recesses, or grooves, orchannels 20 a′ and 21 a′, respectively, which extend in a generallyaxial direction. The aforesaid grooves 20 a′ and 21 a′ delimit, withcorresponding surface portions of the through cavity 14 of the body 2,respective parts of the passageway 15 for the fluid.

In this case, the wall 22 defines one or more first passages for thefluid, having respective inlets 23 a and outlets 23 b for the fluid,each of which is in fluid communication with the outlet end of a groove20 a′ and the inlet end of a groove 21 a′, respectively. Also in thiscase, the inlet 23 a and the outlet 23 b are staggered with respect toone another, for the purposes already explained above.

The transverse wall 22 also defines one or more corresponding secondpassages 24, which are to house at least one intermediate portion 16 aof the body 16, which connects together the two compressible elements 20and 21. Preferentially, also in this case, the passage 24 or passages 24are shaped so as to define a step, or projection, or relief, for thepurposes already described previously.

As already mentioned, in embodiments alternative to that of FIG. 60,recesses or grooves or channels could be defined on the inner surface ofthe through cavity 14 of the body 2—for example, in positionscorresponding to those of the grooves designated by 20 a′ and 21 a′ inFIG. 60—so as to delimit with an outer surface of the compressibleelement 20 and/or 21 a corresponding part of the passageway for thefluid.

FIG. 60 also illustrates how, in various embodiments, one or more firstpassages 23 a-23 b may be defined in the wall 22 in a positionperipheral or eccentric with respect to one or more passages 24.

As may be noted, moreover, also in embodiments where the sensitiveelement 5 has a body made up of a number of parts 5 a, 5 b definingbetween them a cavity C, the through cavity 14 (i.e., the body 2 thatdefines it), may be advantageously shaped so as to present, downstreamof the transverse wall 22, a housing portion 26 for at least part of theupper compressible element 21.

FIG. 60 likewise illustrates how, in possible embodiments, the cavity Cof a sensitive component 5 that is defined between a main body 5 b and acorresponding membrane 5 b does not necessarily have to be isolated fromthe external environment (such as in the case of FIG. 59, whichillustrates a pressure sensor of a type commonly referred to as“absolute” pressure sensor).

As may be noted, in fact, in the case exemplified in FIG. 60, the body 5b of the sensitive element 5 has a passage 5 b′, designed to set theinside of the cavity C in communication with the external environment soas to have available a reference pressure—here the ambient pressure—andthereby providing a pressure sensor of the type commonly referred to as“relative” pressure sensor. In the case exemplified, the passage 5 b′sets the cavity C in communication with an environment internal to thehousing structure 2-3, which is in turn in communication with theoutside via a passage of the casing body 2-3: such a passage, presentalso in various other embodiments, is designated by 3 b only in FIG. 60.It should moreover be noted that, in the case exemplified (and unlikethe device exemplified in FIG. 59), the body 5 b is shaped at its lowerend so as to define a small recess (not represented), which hencedetermines the presence of a cavity C having a volume slightly largerthan in the case of FIG. 59.

Of course, one or more of the characteristics described with referenceto FIG. 60 may be applied also to the case of devices that include justone of the compressible element 20 and the compressible element 21, orelse two elements 20 and 21 configured as separate components.

In various embodiments, which are autonomously inventive, i.e., even inthe absence of a transverse wall of the type designated by 22, thepressure-sensor device comprises or envisages means suitable forformation of structural or chemical bonds, i.e., an improved adhesion,between at least a part of a casing body thereof (such as the supportingbody 2) and an overmoulded or co-moulded compressible body (such as abody 16, or 20, or 21). The aforesaid improved adhesion is preferablyobtained:

using for the two components in question materials that are chemicallyand/or structurally compatible with one another (e.g., a body of thetype designated previously by 2 may be made at least in part of apolyamide PA or a polyphthalamide PPA, and a compressible body of thetype designated by 16, or 20, or 21 may be made at least in part of asilicone, or a silicone elastomer, or a silicone rubber); and/or

using a adhesion promoter (primer) integrated in or distributed at asurface part of at least one of the components (e.g., the body 2) priorto moulding thereon of the other component (e.g., the compressible body16).

In various embodiments, which are in themselves inventive, the materialitself of at least one of the supporting body 2 and the compressiblebody 16, or 20, or 21 comprises or integrates a promoter designed tofavour adhesion or a chemical bond (such as a covalent or ionic orion-bridge bond) with the material of the other one of the supportingbody 2 and the compressible body 16, or 20, or 21. For example, a bodyof the type previously designated by 2 may be obtained at least in partwith a polyamide PA or a polyphthalamide PPA, and a compressible body ofthe type of those indicated with 16 or 20 or 21 may be obtained at leastin part with a silicone, or a silicone elastomer, or a silicone rubber.A configuration of this type is schematically illustrated in FIGS. 61and 62, where the small circles represent the aforesaid possiblechemical or structural bonds. In the example, pairs of circles thatintersect represent possible covalent bonds and pairs of circles facingwith opposite polarity represent possible ion and/or ion-bridge bonds.In the example illustrated, the surface of the through cavity 14—i.e.,the interface surface between the body 2 and the body 16—presentschemical bonds with the body 16 (or the element 20, in the case of FIG.62). FIG. 62 moreover highlights the case of a thrust on thecompressible body 16 or 20 by the pressurized fluid, where:

the vectors represented by the vertical or axial arrows representschematically the force of thrust of the fluid, which tends to move anddeform the compressible element 16 (or 20) substantially in the axialdirection of the cavity 14, towards the sensitive component 5; and

the vectors represented by the horizontal arrows or arrows radial withrespect to the interface between the bodies 2 and 16 (or 20) representschematically the forces of the aforesaid chemical bonds, which tend tomaintain surfaces of the bodies 2 and 16 (or 20) fixed with respect toone another, thus opposing the aforesaid axial force or shearing force,and hence opposing deformation and/or extrusion of the compressible bodytowards the sensitive element 5 under the thrust of the fluid.

In other embodiments in themselves inventive, set between the materialof the supporting body 2 and the material of the compressible body 16,or 20, or 21 is an adhesion-promoter material or substance, which formsa thin intermediate layer, preferably comprised between 1 μm and 20 μm,which has the purpose of causing the two aforesaid materials to adheretogether, i.e., creating a chemical bond (such as a covalent or ionic orion-bridge bond), on one side with respect to the material of thesupporting body 2 (e.g., a PA or a PPA) and on the other side withrespect to the material of the compressible body 16, or 20, or 21 (e.g.,a silicone, or a synthetic rubber, or an elastomer). A configuration ofthis type is schematically illustrated in FIG. 63, where the chemical orstructural bonds, also in this case represented schematically by pairsof intersecting or facing small circles, are provided:

on one side, between the layer Pr of the adhesion promoter and thematerial of the body 2, and

on the other side, between the layer Pr of the adhesion promoter and thebody 16 (or 20).

(The thickness of the layer Pr has been deliberately increased forreasons of greater clarity of representation).

In configurations of the type represented schematically in FIG. 63, theforces of the aforesaid chemical bonds tend to maintain fixed together asurface of the body 2 (in particular, of the through cavity 14) and acorresponding first surface of the layer of material Pr, as well as tomaintain fixed together a second surface (opposite to the first surface)of the layer of material Pr and a surface of the body 16 (or 20), inthis way opposing axial forces or shearing forces exerted by the fluidon the compressible body 16 (or 20), and hence opposing deformationand/or extrusion of the compressible body in the direction of thesensitive component 5, as represented schematically in FIG. 62.

Obviously, the inventive ideas just set forth above with reference toFIGS. 61-63 apply also in relation to surfaces of the transverse wall 22and/or of the passage or passages 24 (including the projecting wall 25or 25′), and/or to surfaces of the connection portion or portions 16 aof the compressible body 16, and/or to surfaces of the housing portion26 and/or of the corresponding compressible element 21.

According to variants not represented, the at least one inlet 23 a andthe at least one outlet 23 b may comprise staggered passages and/orpassages shaped so as to define a tortuous path that are obtained inparts of the supporting body 2 different from the ones exemplified inthe drawings; for this purpose, what has been described previously at apreferential level with reference to the portion 2 c of the body 2 andto the wall 22 is to be understood as referring also to other regions ofthe body 2.

In possible variant embodiments (not represented), the passages that areto house the material that forms the connection portion or portionsbetween the internal and external compressible elements are defined in asubstantially central region of a wall transverse with respect to thethrough cavity of the supporting body, relative to one or more firstpassages for the fluid.

Individual characteristics outlined with reference to embodimentsdescribed previously may be combined together in other embodiments. Forinstance, characteristics described with reference to the examples ofFIGS. 1-58, regarding devices with a sensitive element having amonolithic sensor body, may be combined and/or adapted to obtain deviceswith a sensitive element having a sensor body comprising a number ofparts, of the type described with reference to FIGS. 59-60.

1. A pressure sensor device comprising: a pressure-sensitive component,having a sensor body that includes an elastically deformable membranepart and at least one detection element suitable for detecting adeformation of the elastically deformable membrane part; a housing orsupporting structure of the pressure-sensitive component, having atleast one passageway for a fluid the pressure of which is to bedetected, the housing or supporting structure comprising: a housing orsupporting body with respect to which the sensor body is positioned insuch a way that its elastically deformable membrane part is exposed tothe fluid exiting the at least one passageway, the housing or supportingbody having at least one through-cavity, a compressible body, configuredfor compensating possible variations of volume of the fluid, wherein thehousing or supporting body has a first body portion comprising atransverse wall of the through-cavity in which is defined at least onefirst passage belonging to the passageway for the fluid, wherein atleast one second passage is defined in the transverse wall and thecompressible body is an element over-moulded or co-moulded with respectto the housing or supporting body, that has respective opposite portionswhich extend in positions corresponding to opposite sides of thetransverse wall, said opposite portions being connected to one anothervia at least one intermediate portion of the compressible body that thatextends through the at least one second passage, wherein the first bodyportion is shaped to define at least one step or one projection or onerelief which determines at least one of: a cross-sectional narrowing ofthe at least one second passage, configured to define a correspondingcross-sectional reduction of the at least one intermediate portion ofthe compressible body, and a development of the at least oneintermediate portion of the compressible body which is generallytortuous or comprises a number of stretches substantially angled to eachother.
 2. The device according to claim 1, wherein the compressible bodydefines at least one of: a first compressible element, set at leastpartially within the through-cavity of the housing or supporting bodyupstream of the transverse wall, which delimits at least in part atleast one respective duct for the fluid having an inlet end and anoutlet end, a second compressible element, set downstream of thetransverse wall, the second compressible element having a top surfacefacing the elastically deformable membrane part of the sensor body anddelimiting at least in part at least one respective duct for the fluidhaving an inlet end and an outlet end.
 3. The device according to claim2, wherein the compressible body defines in a single piece the firstcompressible element and the second compressible element, which areconnected to one another via the at least one intermediate portion. 4.The device according to claim 1, wherein the first body portioncomprises at least one of: at least one projecting or cantilever wall ofthe through-cavity, downstream of the transverse wall, the at least oneprojecting or cantilever wall extending towards the inside of thethrough-cavity to define at least in part the at least one step, and atleast one cross-sectional narrowing of the through-cavity downstream ofthe transverse wall, which defines at least in part the at least onestep.
 5. The device according to claim 1, wherein the first body portionis shaped to define at least one of: at least one step or projection orrelief at at least one end region of the at least one second passage, atleast two steps or projections or reliefs at opposite end regions of theat least one second passage.
 6. The device according to claim 1, whereinthe at least one second passage comprises a first cavity having a bottomand a second cavity having a bottom, which are defined at opposite sidesof the transverse wall and are formed so as to intersect each other in alateral direction.
 7. The device according to claim 2, wherein: thepassageway for the fluid comprises the at least one duct delimited atleast in part by the compressible body, the at least one first passagehas at least one respective inlet for the fluid and at least onerespective outlet for the fluid, at least one of the at least one inletand the at least one outlet being in fluid communication with the atleast one duct delimited at least in part by the compressible body, andthe at least one inlet and the at least one outlet of the at least onefirst passage are arranged to define a tortuous path for the fluid, theat least one inlet and the at least one outlet.
 8. The device accordingto claim 7, wherein: the at least one inlet of the at least one firstpassage is in fluid communication with the outlet end of the at leastone duct delimited at least in part by the first compressible element,and/or the at least one outlet of the at least one first passage is influid communication with the inlet end of the at least one ductdelimited at least in part by the second compressible element.
 9. Thedevice according to claim 2, wherein the at least one first passage hasat least one respective inlet and at least one respective outlet whichcomprise a first cavity and a second cavity each having a bottom, whichare defined at opposite sides of the transverse wall and are formed soas to intersect each other in a lateral direction.
 10. The deviceaccording to claim 7, wherein the at least one inlet of the at least onefirst passage comprises a first inlet and a second inlet staggered toeach other and in fluid communication with one and the same outlet ofthe at least one first passage, the outlet being staggered with respectto the first inlet and the second inlet, or else the at least one outletof the at least one first passage comprises a first outlet and a secondoutlet staggered to each other and in fluid communication with one andthe same inlet of the at least one first passage, the inlet beingstaggered with respect to the first outlet and the second outlet. 11.The device according to claim 10, wherein: the at least one duct of thefirst compressible element comprises two ducts, whose outlet ends are influid communication with the first inlet and the second inlet of the atleast one first passage, respectively, or else the at least one duct ofthe second compressible element comprises two ducts, whose inlet endsare in fluid communication with the first outlet and the second outletof the at least one first passage, respectively.
 12. The deviceaccording to claim 1, wherein the transverse wall defines at least oneof: a plurality of said first passages for the fluid, a plurality ofsaid second passages through which there extend respective intermediateportions of the compressible body.
 13. The device according to claim 2,comprising the second compressible element, wherein the through-cavityis shaped to define, downstream of the transverse wall, a housingportion within which the second compressible element is at leastpartially housed.
 14. The device according to claim 1, wherein thethrough-cavity has a peripheral surface shaped to define one or morereliefs performing a function of retention of the at least onecompressible element.
 15. The device according to claim 1, comprisingmeans for causing an adhesion or bond between at least one part of thehousing or supporting body and at least one part of the at least onecompressible element, where preferably: a material of at least onesurface part of at least one of the housing or supporting body and theat least one compressible element is chemically and/or structurallycompatible with a material of at least one surface part of the other oneof the housing or supporting body and the at least one compressibleelement, and/or a material of at least one surface part of at least oneof the housing or supporting body and the at least one compressibleelement comprises or integrates a primer suitable for favouring saidadhesion or bond with a material of at least one surface part of theother one of the housing or supporting body and the at least onecompressible element, and/or between a material of the housing orsupporting body and a material of the at least one compressible elementis set a layer of a primer suitable for favouring said adhesion or bond.16. A pressure sensor device comprising: a pressure-sensitive component,having a sensor body that includes an elastically deformable membranepart and at least one detection element suitable for detecting adeformation of the elastically deformable membrane part; a housing orsupporting structure of the pressure-sensitive component, having atleast one passageway for a fluid the pressure of which is to bedetected, the housing or supporting structure comprising: a housing orsupporting body with respect to which the sensor body is positioned insuch a way that its elastically deformable membrane part is exposed tothe fluid exiting the at least one passageway, the housing or supportingbody having at least one through-cavity, at least one compressibleelement, which is configured for compensating possible variations ofvolume of the fluid.
 17. (canceled)
 18. The device according to claim 2,wherein at least one of the first compressible element or the secondcompressible element is in contact with the transverse wall.
 19. Thedevice according to claim 7, wherein the at least one inlet and the atleast one outlet of the at least one first passage are in staggeredpositions in a lateral direction.
 20. The device according to claim 15,wherein: a material of at least one surface part of at least one of thehousing or supporting body and the at least one compressible element ischemically and/or structurally compatible with a material of at leastone surface part of the other one of the housing or supporting body andthe at least one compressible element, and/or a material of at least onesurface part of at least one of the housing or supporting body and theat least one compressible element comprises or integrates a primersuitable for favouring said adhesion or bond with a material of at leastone surface part of the other one of the housing or supporting body andthe at least one compressible element, and/or between a material of thehousing or supporting body and a material of the at least onecompressible element is set a layer of a primer suitable for favouringsaid adhesion or bond.